Sort of, but not really. In a real-steel magazine, "double stack" means the rounds are stacked in a staggered fashion in the same chamber of the magazine and come out of the same set of feed lips.

In a Zetamag, there is a ten round stack on one end, then you remove the mag, flip it, and there's a ten round stack on the other. I don't like to harp on semantics but people who know firearms will probably get the wrong idea if you describe this to them as a "double stack magazine".

We cleaned them out at Living Legends. People were buying 4-6 at a time like wild fire. I used them during the Magfed Games on Friday. Absolutely fantastic. When I am play pistol again, these will be mandatory.